1. Field of the Invention
The present invention generally relates to dispensers and more particularly to an inexpensive (i.e. disposable) dispensing device and the method of making the device which delivers an accurate and uniform drop of liquid of a given size (i.e. 30, 40, or 50 microliters) and which includes an integral paddle stirrer. This device is very useful with a number of tests that require a small amount of liquid to be dispensed and spread over an area or mixed with another sample.
2. Discussion of the Prior Art
Various types of devices are known for dispensing liquids in the form of drops or definite volumetric quantity, such as standard glass and plastic pasteur pipettes, serological pipettes, calibrated capillary tubes, conventional medicine or eye droppers, air and positive displacement pipettes and syringes. These devices are somewhat inaccurate or expensive and do not incorporate a paddle stirrer. Therefore, they are generally unsuitable for this application.
U.S. Pat. No. 3,811,603 granted May 21, 1974 to L. C. Felton, disclosed a combined disposable liquid dropper and stirrer. The device, however, has certain disadvantages. Liquid is drawn into the tube and dispensed from the tube by grasping the tube at any point along its length and squeezing it between two fingers. Since the size of fingers can vary considerably from one person to another it is apparent that the amount of liquid drawn into the tube and the size of the drop will vary accordingly. The drop size variations of this device can be seen from the graphic illustration in drawing FIG. 5 of the above numbered patent. This device according to its claims and description is also limited to a single drop.
Other U.S. Patents of which the present inventor is aware and which comprise the most pertinent art known to the inventor are as follows: U.S. Pat. Nos. D228,492 issued to Cohen; D250,599 and D260,434 issued to the present inventor; 2,129,627 issued to Sands; 2,656,070 isued to Linder; 3,834,241 issued to Garren; and 4,212,204 issued to the present inventor.